This invention relates to wafer containers and more particularly it relates to sealable wafer enclosures having doors with latch mechanisms.
Processing of semi-conductor wafers into finished electronic components typically requires many processing steps where the wafers must be handled and processed. The wafers are very valuable, and are extremely delicate and easily damaged by physical and electrical shocks. In addition, successful higher yield processing requires the utmost in cleanliness, freedom from particulates and other contaminants. As a result, specialized containers or carriers have been developed for use during processing, handling and transport of wafers. These containers protect the wafers from physical and electrical hazards, and are sealable to protect the wafers from contaminants. Such wafer carriers or containers generally comprise an enclosure having a number of wafer holding shelves inside. One side of the container is open for access, and is closed by a door. The door has a latch mechanism to securely retain and seal it in place. Normally, the latch mechanism is enclosed to protect it from damage and accidental actuation.
Although wafer enclosures are used in clean environments, undesirable contaminants accumulate on and in the enclosure over time. Particulate contaminants are generated through frictional contact between parts of the enclosure and in the operation of loading and unloading wafers from the enclosure. Accordingly, an important characteristic for wafer containers is that they must be thoroughly cleanable to ensure that process cleanliness is maintained. Cleaning is generally accomplished with a liquid solution, and the parts are dried afterward with compressed air or other gas.
Latch mechanism enclosures present particular problems in efficient cleaning of wafer carriers. In prior art carriers, such as those shown in U.S. Pat. No. 5,915,562 to Nyseth and Krampotich, and U.S. Pat. No. 5,957,292 to Mikkelsen, et. al. for example, each of which are fully incorporated herein by reference, the latch mechanisms are located in cavities in the door that are covered by flat panels. Although such enclosure helps to isolate and contain particle generation from the latch mechanism itself, access to the latch mechanism area for cleaning and drying is limited. In addition, relatively large cavities with correspondingly large interior surface areas are formed around the latch components. The combination of limited access with large surface areas and volumetric areas makes it generally infeasible to effectively clean and dry the mechanism area with the enclosure in place. Also, large cavities may retain a correspondingly larger amount of particulate or other contaminant material. As a result, at least partial disassembly of the mechanism enclosure is necessary. This can be a tedious, labor-intensive process that can introduce process inefficiencies and delays. Accordingly, a mechanism enclosure that allows increased access to the mechanism components and that offers a reduced surface area inside the enclosure is desirable.
One way of reducing the interior surface area of the latch enclosure is to exclude unnecessary areas by conforming the enclosure to the latch components it protects. A wafer carrier door having a latch mechanism cover that more closely conforms to the contour of the latch mechanism was disclosed in PCT Application No. WO 01/04022 A1. The disclosed mechanism cover does not cover the entire latch cavity, but rather covers only the latch arms, the motion translation mechanism and a portion of the manual handle. The disclosed mechanism cover conforms to the contour of the latching arms for only a portion of one side of the latching arms. Thus, there are significant areas unnecessarily captured under the mechanism cover, particularly the areas between the latching arms and door margins. These areas remain difficult to clean and dry with the mechanism cover in place.
Moreover, manufacturing, and subsequent assembly, and disassembly of wafer carrier doors is sometimes complicated by previous designs of the latch mechanisms and latch mechanism covers. Typically, the latch mechanism components are retained and guided by structures formed in the door chassis. The mechanism cover merely serves to cover the latching components in such designs, and does not typically function to guide or laterally retain the components. It is generally necessary to form retaining and guide structures for latch components on the door chassis itself in such designs. These structures may be difficult to form, add complexity to the door chassis, and may complicate the assembly and disassembly process.
What is needed is an improved wafer container and door that overcomes the difficulties presented by the prior art designs.
The present invention is a wafer container and improved door. The door has a latch mechanism cover that retains and guides the latch mechanism components. The latch mechanism cover may be form fitted to the shape of the latch mechanism, thus minimizing the surface area of the door chassis captured under the mechanism cover, and thereby reducing the amount of particulates and other contaminants retained in the structure of the door. The retaining and guiding function of the latch mechanism cover may eliminate the need for guiding and retaining structures on the door chassis, thereby simplifying manufacture, assembly and disassembly of the door. Moreover, the latch mechanism cover may have a plurality of apertures for providing cleaning access to areas underneath.
Thus, the invention generally includes a wafer container and door. The door generally includes a door chassis with at least one latch mechanism. The latch mechanism has at least one slidable latch arm. A latch mechanism cover disposed over the latch mechanism, and the cover includes a panel portion substantially covering the latch mechanism and having an inner surface confronting the latch mechanism. A pair of spaced-apart guide portions projects from the inner surface of the panel portion adjacent the latch arm. The latch arm is longitudinally slidably disposed between the guide portions, which are adapted to slidably guide and locate the latch arm.
An object and advantage of the invention is a latch mechanism cover that provides protection for the latch mechanism parts.
Another object and advantage of the invention is a latch mechanism cover that retains and guides the latch mechanism parts.
Another object and advantage of the invention is a latch mechanism cover that allows cleaning and drying of area under the cover while the cover remains in place.
Yet another object and advantage of the invention is to provide a latch mechanism cover with apertures forming an open architecture mechanism cover that improves cleanability of the portions of the door located under the mechanism cover.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.